Simplify the following expression: $t = \dfrac{10k}{9} - \dfrac{k}{8}$
Explanation: In order to subtract expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $9$ and $8$ $\lcm(9, 8) = 72$ $ t = \dfrac{8}{8} \cdot \dfrac{10k}{9} - \dfrac{9}{9} \cdot \dfrac{k}{8} $ $t = \dfrac{80k}{72} - \dfrac{9k}{72}$ $t = \dfrac{80k -9k}{72}$ $t = \dfrac{71k}{72}$